I'd like to announce the creation of a new mailing list dedicated to centralising discussion regarding MediaWiki internationalisation. Details can be found at http://mail.wikimedia.org/mailman/listinfo/mediawiki-i18n.
MediaWiki's support for multiple languages, and the provided translations, is dependent upon volunteers to maintain the language files the software uses, and it's fair statement to point out that a lot of these are out of date or missing entries.
When a developer adds a new feature which requires an interface message, it's added to the English-language localisation files, and sometimes the files corresponding to another language, if spoken, e.g. I might add a new feature and provide English and French messages. This doesn't help other languages, such as German or Russian. Likewise, removals or renaming of messages don't propagate to other languages (although I intend to write a couple of quick scripts to help make this convenient), leaving obsolete messages behind.
What would be awesome is if each language had a maintainer who was active in helping to keep their specific language up to date. Some languages do seem to have de facto maintainers; Rotem Liss, for example, has adopted Hebrew, and we receive frequent patches from him in response to updates we make.
I'd therefore like to take this opportunity to extend a welcome to anyone interested in helping to clean up their spoken language's translations to join the list and see what it's all about and what needs doing. I am, of course, happy to answer questions prospective maintainers have, and Niklas Laxström is another figure you might want to contact.
Rob Church